There I was, at 6 A.M. on the chilly day after Christmas, jammed in the vestibule of a well-known national department store, all because a badly worded newspaper ad had lured me and dozens of others to arrive for the after-holiday sale an hour early. No one let us in the store; no one apologized later when I sent an e-mail complaint to the company's website. Luckily for the store, I wasn't quite aware of how much damage I could do to its reputation online in...